JPH1041244A - Laser treating apparatus and manufacturing method of semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser treating apparatus capable of improving the crystallinity of a work such as semiconductor film, making the crystallinity uniform and attaining a high through-put. SOLUTION: A laser treating apparatus comprises an excimer laser unit 10 capable of emitting pulse-like and parallel laser beams, and stage 20 having means for moving a work 31 mounted thereon, relative to the beams, approximately perpendicularly to the length of the linear beams, thereby the beam irradiating regions of the work 31 being different.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a laser processing apparatus and a method for manufacturing a semiconductor device.

[0002]

2. Description of the Related Art A polycrystalline silicon thin film composed of a group of silicon single crystal particles formed on a substrate is used for various semiconductor devices such as a thin film transistor (hereinafter abbreviated as TFT), a semiconductor device using SOI technology, and a solar cell. Have been.

In the field of semiconductor devices, for example, T
A stacked SRAM using FT as a load element has been proposed. Further, TFTs are also used in liquid crystal panels for LCDs. For example, in a TFT requiring high performance in electrical characteristics such as carrier mobility (μ), conductivity (σ), on-current characteristics, sub-threshold characteristics, and on / off current ratio, a silicon single crystal is usually used. A polycrystalline silicon thin film composed of particles is used. Then, by increasing the size of the silicon single crystal particles (increase in particle size) and reducing the twin density to lower the trap density in the silicon single crystal particles, the characteristics of the SRAM and TFT are improved. Efforts are underway to make this happen. Also, for example, L
In the case of forming a TFT for forming a liquid crystal panel for CD, there is a strong demand for an increase in the size of the transparent insulating substrate and a reduction in manufacturing cost.

In order to improve the electrical characteristics of such a polycrystalline silicon thin film, an ELA technique (Excimer Laser Annea
l, melt crystallization technology using an excimer laser) is drawing attention. In the ELA technique, an amorphous silicon thin film can be crystallized at a relatively low temperature by irradiation with an excimer laser beam, so that a low-cost transparent insulating substrate such as a low-melting glass can be used.
Further, by irradiating the amorphous silicon thin film with overlapping pulsed linear excimer laser beams, the amorphous silicon thin film having a relatively large area can be efficiently converted to a polycrystalline silicon thin film. Such a technique is described, for example, in the document “Crystallization of Amorpho”.
us Silicon By Excimer Laser Annealing with a Line
Shaped Beam Having a Gaussian Profile ”, YM Jho
n, et al., Jpn. J. Appl. Phys. Vol. 33 (1994), pp.
L1438-l1441 and the literature “Fabrication of Low-Temperatu
re Bottom-Gate Poly-Si TFTs on Large-Area Substrat
e by Linear-Beam Excimer Laser Crystallization and
Ion Doping Method ”, H. Hayashi, et al., IDEM 95-
829.

[0005] Here, the term “overlap” means that the region of the object irradiated with the pulsed laser beam and the region of the object irradiated next with the pulsed laser beam overlap. It means there is. When the width of the linear laser beam is W and the amount of one movement of the laser beam is L (where L ≦ W), the overlap amount OL is
It can be represented by (1-L / W). On the other hand, the moving ratio R of the laser beam can be represented by L / W.

[0006]

In order to improve the crystallinity of the polycrystalline silicon thin film or to make the crystallinity uniform and to improve the performance of the TFT, for example, the overlap amount of the pulsed excimer laser beam is required. OL needs to be increased. Alternatively, refer to the document “A Fabrication of H
omogenious Poly-Si TFT's Using Excimer Laser Annea
ling ”, I. Asai, et al, Extended Abstracts of the
1992 International Conference on Solid State Devic
As is known from es and Materials, Tsukuba, 1992, pp. 55-57, it is necessary to perform two irradiations of the excimer laser beam while changing the energy density of the excimer laser beam. In recent years, an excimer laser device (for example, a pulse frequency of 300 Hz and an irradiation energy of 1 J /
cm ² ) has been developed, but performing irradiation with an excimer laser beam twice is extremely effective in manufacturing a high-performance TFT.

However, these operations have low throughput and cannot achieve high productivity. For example, the width W of the laser beam is 0.5 mm, the amount of one movement L of the laser beam is 0.05 mm, and the overlap amount OL is
= 0.90, pulse frequency 200 Hz, length 40
When the 0 mm amorphous silicon thin film is scanned once, the time required for scanning is 400 / 0.05 / 200 = 40 seconds. Therefore, two scans require 80 seconds or more.

Accordingly, an object of the present invention is to improve the crystallinity of an object to be processed such as a semiconductor thin film,
Another object of the present invention is to provide a laser processing apparatus capable of making crystallinity uniform and achieving a high throughput, and a method of manufacturing a semiconductor device using the laser processing apparatus.

[0009]

According to the present invention, there is provided an excimer laser apparatus capable of emitting a plurality of linear laser beams in pulses and in parallel with each other. And (b) a stage provided with a moving means for mounting the object to be processed and moving a relative position between the laser beam and the object to be processed in a direction substantially perpendicular to the longitudinal direction of the linear laser beam; , And the region where each laser beam irradiates the object to be processed is different.

Alternatively, a method of manufacturing a semiconductor device according to the present invention for achieving the above object comprises: (a) an excimer laser device capable of emitting a plurality of linear laser beams in a pulsed manner and in parallel with each other; , (B) Place the object to be processed,
A stage provided with a moving means for moving a relative position between the laser beam and the object to be processed in a direction substantially perpendicular to the longitudinal direction of the linear laser beam, wherein each laser beam The irradiation region is a method for manufacturing a semiconductor device using a different laser processing apparatus, wherein the object to be processed is formed of a non-single-crystal silicon layer formed on a base, and a plurality of laser beams is applied to the non-single-crystal silicon layer. It is characterized in that a crystallized silicon layer is formed by irradiating in a pulsed manner.

In the method of manufacturing a semiconductor device according to the present invention, the base is made of a silicon oxide film formed on the substrate, and is formed by irradiating the non-single-crystal silicon layer with a plurality of laser beams in a pulsed manner. The method may include forming a channel region and a source / drain region in the crystallized silicon layer. In addition, as the substrate, a silicon semiconductor substrate, a quartz substrate, a soda lime glass substrate, an alkali-free glass substrate, a borosilicate glass substrate, and the like can be given, and the crystallization is performed at a relatively low temperature by using the laser processing apparatus of the present invention. Since a silicon layer can be formed, a glass substrate is preferably used in terms of reduction in manufacturing cost of a semiconductor device.

Here, the non-single-crystal silicon layer specifically means an amorphous silicon layer or a polycrystalline silicon layer. When the non-single-crystal silicon layer is an amorphous silicon layer, the crystallized silicon layer means a polycrystalline silicon layer or a single-crystal silicon layer. Further, when the non-single-crystal silicon layer is a polycrystalline silicon layer, the crystallized silicon layer means a single-crystal silicon layer.

As a semiconductor device manufactured by the method of manufacturing a semiconductor device according to the present invention, for example, a top gate type or bottom gate type thin film transistor used for a liquid crystal panel for LCD, a semiconductor device using SOI technology (for example, Various semiconductor devices such as a thin film transistor as a load element of a stacked SRAM and a MOS semiconductor device can be exemplified.

It is preferable that the relative position between the laser beam and the object be moved while the laser beam is not irradiating the object. That is, it is preferable to move the relative position between the laser beam and the object between the emission of the pulsed laser beam. As the excimer laser device, for example, a XeCl excimer laser device having a wavelength of 308 nm can be exemplified.
The width (W) of a linear laser beam measured along the moving direction
Is arbitrary, and may be, for example, 40 μm to about 1 mm. The distance D (gap) between regions irradiated with the object to be processed by the laser beam or the amount of movement L of the relative position between the laser beam and the object to be processed is determined by the width of the linear laser beam. It may be determined based on (W), the required overlap amount OL, the irradiation energy of the laser beam, the pulse frequency of the laser beam, and the like. Note that the overlap amount OL is represented by 1−L / W (where L ≦ W). Depending on the object to be processed, the overlap may not be required.

One laser beam emitted from the laser generator provided in the excimer laser device may be divided into a plurality of laser beams, or a plurality of laser generators may be provided, and A laser beam may be emitted. The irradiation energy amount, pulse width, pulse frequency, and linear laser beam width (W) of each laser beam may be the same or different. Further, each pulsed laser beam may or may not be synchronized.

Although the length of the linear laser beam is arbitrary, it is preferable that the length of the linear laser beam is about the width of the workpiece from the viewpoint of improving the throughput. The width of the object to be processed is
The dimension of the workpiece measured along a direction parallel to the longitudinal direction of the linear laser beam, and the length of the workpiece is measured along a direction perpendicular to the longitudinal direction of the linear laser beam. This is the size of the object.

It is preferable that the rising of the energy at the longitudinal edge of the linear laser beam is extremely sharp.
It is preferable to further include an attenuator (attenuator), which is a type of interference filter, and a beamformer for uniformizing a laser beam into a rectangular shape.

The excimer laser device may be fixed and the stage may be moved, the stage may be fixed and the excimer laser device may be moved, or both the stage and the excimer laser device may be moved. You may.
The stage may be a so-called XY-stage or XY-table, but is not limited thereto. The moving direction of the relative position between the laser beam and the object does not need to be strictly perpendicular to the longitudinal direction of the linear laser beam.

In the present invention, since an excimer laser device capable of emitting a plurality of linear laser beams in a pulsed manner and in parallel with each other is used, the number of laser beams can be reduced by one laser beam scanning of an object to be processed. The object is irradiated with the laser beam a corresponding number of times. Therefore, heat treatment of the object to be processed can be performed uniformly without lowering the throughput.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings based on embodiments of the present invention (hereinafter simply referred to as embodiments).

Embodiment 1 FIG. 1 shows a conceptual diagram of a laser processing apparatus according to Embodiment 1. This laser processing device
It comprises an excimer laser device 10, a moving means (not shown) composed of a combination of a motor and a gear, and comprises a stage 20 on which an object to be processed is placed.
More specifically, the stage 20 is composed of a well-known XY-stage. The moving means moves the relative position between the laser beam and the object to be processed in a direction substantially perpendicular to the longitudinal direction of the linear laser beam. In FIG. 1, the longitudinal direction of the linear laser beam coincides with the direction perpendicular to the plane of the drawing. FIG. 3 is a schematic perspective view showing a state in which the object 31 is irradiated with two laser beams. In FIG. 3, a processed region 32 obtained by processing the object 31 by the ELA technique is hatched.

The excimer laser device 10 includes a laser generating device 11A that emits a linear laser beam in a pulse shape.
11B, attenuators 12A and 12B, which are a kind of interference filters, beamformers 13A and 13B for making a laser beam uniform in a rectangular shape, and a reflecting mirror 14A.
14B is further provided. The linear laser beam A emitted from the laser generator 11A is applied to the attenuator 1
The object to be processed 31 formed on the substrate 30 mounted on the stage 20 is irradiated via the beamformer 13A and the reflecting mirror 14A. Similarly, the linear laser beam B emitted from the laser generator 11B is formed on the base 30 placed on the stage 20 via the attenuator 12B, the beam former 13B, and the reflecting mirror 14B. The object to be processed 31 is irradiated. The two laser beams A and B are parallel to each other. Then, as shown in FIG. 3, each laser beam A,
The region irradiated with the workpiece 31 differs depending on B.

(Embodiment 2) FIG. 2 shows a conceptual diagram of a laser processing apparatus according to Embodiment 2, and in this laser processing apparatus, there is one laser generating apparatus 11. The pulsed linear laser beam emitted from the laser generation device 11 is split by the half mirror 15 into two laser beams A and B. Split laser beam A
Irradiates an object to be processed 31 formed on a base 30 placed on the stage 20 via an attenuator 12A, a beam former 13A, and a reflecting mirror 14A. Similarly, the split laser beam B is applied to the attenuator 12
B, via the beam former 13B and the reflecting mirror 14B,
The object to be processed 31 formed on the base 30 placed on the stage 20 is irradiated. Also in the laser processing apparatus having this structure, two laser beams A and B
Are parallel to each other and, as also shown in FIG.
The region where the object 31 is irradiated by the laser beams A and B is different.

(Embodiment 3) In Embodiment 3, an n-type thin film transistor having a bottom gate structure was manufactured using the laser processing apparatus described in Embodiment 1. In manufacturing this semiconductor device, first, an insulating layer 4 made of SiO ₂ is formed on the surface of a glass substrate 40.
After forming No. 1, a polycrystalline silicon layer doped with impurities was deposited on the entire surface by a CVD method. Then, the polycrystalline silicon layer is patterned to form the gate electrode 4.
2 was formed. Next, a substrate 43 made of a SiO ₂ layer was formed on the entire surface by CVD. The base 43 made of this SiO ₂ layer also functions as a gate oxide film.

Next, on a substrate 43 composed of a SiO ₂ layer,
Amorphous silicon layer 44 having a thickness of 40 nm as an object to be processed
(Non-single-crystal silicon layer) was formed by a PECVD method (see FIG. 4A). Then, the formed amorphous silicon layer 44 is irradiated with a pulse of an excimer laser beam (see FIG. 4B), and a polycrystalline silicon layer 45 composed of silicon single crystal particles is formed on the SiO ₂ layer 43. A (crystallized silicon layer) was formed (see FIG. 5A). Table 1 below shows the excimer laser beam irradiation conditions and the like. In FIG. 4B, a region of the amorphous silicon layer 44 irradiated with the previous excimer laser beam is indicated by a dotted line, and a region of the amorphous silicon layer 44 irradiated with the excimer laser beam this time is indicated. This is represented by a dashed line. The amorphous silicon layer 44 is irradiated with the laser beam A and the laser beam B.
The distance (gap) D between the regions irradiated with is set to, for example, 0.5 mm.

[0026]

[Table 1] Laser beam A Type: XeCl excimer laser (wavelength 308 nm) Irradiation amount: 320 mJ / cm ² Pulse width: about 26 ns Frequency: about 200 Hz Beam shape: 400 μm width (W ₁ ) × 150 mm length rectangular shape Move Amount L ₁ : 4 μm Moving amount ratio R ₁ : 1% (= 4 μm / 400 μm × 100) Laser beam B Type: XeCl excimer laser (wavelength 308 nm) Irradiation amount: 320 mJ / cm ² Pulse width: about 26 ns Frequency: about 200 Hz Beam shape: rectangular shape of width (W ₂ ) 400 μm × length 150 mm Moving amount L ₂ : 4 μm Moving amount ratio R ₂ : 1% (= 4 μm / 400 μm × 100)

Since hydrogen is usually confined in the amorphous silicon layer 44 formed by the PECVD method, before performing a normal excimer laser annealing process, 400 ° C. × Hydrogen is removed by performing a heat treatment on the amorphous silicon layer for about 2 hours. Without such hydrogen removal treatment, bubbles and voids are generated in the polycrystalline silicon layer when excimer laser annealing treatment is performed. On the other hand, as in the present invention,
The energy density of the first-stage excimer laser is slightly lower than the energy density of the second-stage excimer laser,
By performing the two-stage excimer laser annealing, not only the characteristics of the polycrystalline silicon 45 obtained from the amorphous silicon layer 44 are improved, but also such a hydrogen removing process becomes unnecessary.

Thereafter, the formed polycrystalline silicon layer 45 is formed.
The source / drain region 46 and the channel region 47 are formed by ion-implanting the impurity into the region where the source / drain region is to be formed, and then activating the ion-implanted impurity. Then, an insulating layer 48 made of, for example, SiO _{2 is} deposited on the entire surface by a CVD method, and then the insulating layer 48 above the source / drain region 46 is
An opening was formed using a photolithography technique and an RIE technique. Then, after a wiring material layer made of an aluminum alloy is deposited on the insulating layer 48 including the inside of the opening by a sputtering method, the wiring material layer is patterned to complete the wiring 49 on the insulating layer 48 (FIG. 5 (B)). The wiring 49 is connected to the source / drain region 46 via a wiring material layer embedded in the opening.

Although the present invention has been described based on the embodiments of the present invention, the present invention is not limited to these embodiments. The structure of the laser processing apparatus, the manufacturing conditions of the semiconductor device, and the structure of the semiconductor device described in the embodiment of the invention are merely examples, and the design can be changed as appropriate. In the embodiment of the invention, two laser beams are applied to the object, but three or more laser beams may be applied to the object. The object to be processed by the laser processing apparatus of the present invention is not limited to the amorphous silicon layer, and any object to be processed can be heat-treated, and is applied only to the manufacture of a semiconductor device. Instead, the present invention can be applied to, for example, manufacturing of a solar cell. Further, the stage may be fixed and the excimer laser device itself may be moved, or the relative position between the laser beam and the object to be processed may be moved by rotating a reflecting mirror provided in the excimer laser device. Good.

In the description of the method for manufacturing a semiconductor device,
Although the amorphous silicon layer is formed on the SiO ₂ layer, a polycrystalline silicon layer may be formed instead. When irradiating the amorphous silicon layer with a pulse of an excimer laser beam, the substrate may be heated. In some cases, for example, the surface of the amorphous silicon layer may be planarized by performing etch-back.

[0031]

According to the present invention, 1% is applied to the object to be treated.
By performing the laser beam scanning twice, the object to be processed can be irradiated with the laser beam the number of times corresponding to the number of laser beams, so that the throughput is not reduced and the heat treatment of the object is performed. It can be performed uniformly.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a laser processing apparatus according to the present invention.

FIG. 2 is a conceptual diagram of a laser processing apparatus of the present invention having a structure different from that shown in FIG.

FIG. 3 is a schematic perspective view showing a state where two laser beams are irradiating an amorphous silicon layer as an object to be processed.

FIG. 4 is a schematic partial cross-sectional view of a substrate and the like for describing a method of manufacturing a semiconductor device according to a third embodiment of the present invention.

FIG. 5 is a schematic partial cross-sectional view of a substrate and the like for illustrating a method of manufacturing a semiconductor device according to a third embodiment of the present invention, following FIG. 4;

[Explanation of symbols]

10. Excimer laser device, 11, 11A, 11B
... Laser generators, 12A, 12B ... Attenuators, 13A, 13B ... Beam formers, 14A, 1
4B: Reflecting mirror, 15: Half mirror, 20 ...
・ Stage, 30 ・ ・ ・ Base, 31 ・ ・ ・ Object, 3
2 ... polycrystalline silicon layer, 40 ... glass substrate, 4
DESCRIPTION OF SYMBOLS 1 ... Insulating layer, 42 ... Gate electrode, 43 ... Base, 44 ... Amorphous silicon layer, 45 ... Polycrystalline silicon layer, 46 ... Source / drain region, 47・
-Channel region, 48 ... insulating layer, 49 ... wiring 4
9

Claims (3)

[Claims] 1. An excimer laser device capable of emitting a plurality of linear laser beams in a pulsed manner and in parallel with each other.
And (b) a stage provided with a moving unit for mounting the object to be processed and moving a relative position between the laser beam and the object to be processed in a direction substantially perpendicular to the longitudinal direction of the linear laser beam; A laser processing apparatus, comprising: a laser beam irradiation area for irradiating an object to be processed; 2. An excimer laser device capable of emitting a plurality of linear laser beams in a pulsed manner and in parallel with each other.
And (b) a stage provided with a moving unit for mounting the object to be processed and moving a relative position between the laser beam and the object to be processed in a direction substantially perpendicular to the longitudinal direction of the linear laser beam; A method for manufacturing a semiconductor device using a different laser processing apparatus, wherein each laser beam irradiates an object to be processed with a different laser processing apparatus. Forming a crystallized silicon layer by irradiating the non-single-crystal silicon layer with a plurality of laser beams in a pulsed manner. 3. The substrate comprises a silicon oxide film formed on a glass substrate, and a non-single-crystal silicon layer is irradiated with a plurality of laser beams in a pulsed manner to form a channel region on the crystallized silicon layer. 3. The method for manufacturing a semiconductor device according to claim 2, wherein a source / drain region is formed.